I've had the FM Recorder for about 3 weeks now, and a daily build of
Rockbox for about 2 weeks, and I have searched most FAQs and bug
reports and have not found this issue...

I charge the jukebox and the Archos hardware/firmware that kicks in
when only charging says it is charged, but Rockbox has a battery icon
that appears to be about 3/4 to 7/8 full, even though it should be
fully charged... now when I was using the archos firmware, it would
show fully charged, but would be incredibly sporadic during playing -
switching between files, etc..., at some times even shutting it off,
so Rockbox is definitely better in that aspect, but I wanted to get
info on it not showing a full battery...